Chemistry of Essential Oils

COMPOSITE 297

OIL OF CARLINA.

This oil is distilled from the root of the thistle Carlina acaulis,

indigenous to Central Europe. The yield is about 1*5 to 2 per cent.

It is a dark-coloured oil of aromatic taste and odour, having the follow-

ing characters :—

Specific gravity 1-030 to 1-040

Optical rotation - 3° „ - 8°

Refractive index 1-5560 „ 1-5700

Acid value 1. 2 ,, 3

Ester „ 4 „ 5

This oil has often been examined chemically, but a careful inspection

of the figures obtained shows that the results are not reliable.

The oil has been, however, carefully investigated by Semmler.^1 It

•contains about 15 per cent, of a monocyclic sesquiterpene, C15H24, boiling

at 140° at 20 mm., and of specific gravity 0*8733 and refractive index

T4920. An oxide, termed " Carlina oxide," C^H^O, of specific gravity

1*066 and refractive index 1*5860, forms the principal constituent of the

oil. It is a complex furane derivative of the constitution C 6 H 5. CH : C :

CH. (C 4 H 3 O). Semmler has also isolated a sesquiterpene C 15 H 24 which

he terms carlinene, and a crystalline solid body. Traces of palmitic acid

appear to be present.

OIL OF COSTUS BOOT.

The root of Aplotaxis Lappa, a plant indigenous to Eastern India,

yields about 1 per cent, of an oil with a characteristic odour recalling

that of orris or violets. This plant, named as above by Decaisne, is

identical with Aplotaxis auriculata (De Candolle), Aucklandia Costus

{Falconer), and Saussurea lappa (Clarke). It grows at elevations of

7000 to 12,000 ft. on the north-western Himalayas, being found freely

AS far east as Sikkim and as far west as Kashmir and Lahore. The oil

is of a light yellow colour, having the following characters:—

Specific gravity

Optical rotation.

Acid value ....

Ester „....

,, „ (after acetylation)

0-940 to 0-995 (rarely to 1-010)

+ 13° to + 25°

8 „ 25

55 „ 115

105 „ 162

It commences to boil at 275°, and about half distils over below 315°,

when decomposition takes place. On keeping, the oil develops an

unpleasant odour.

The oil has recently been exhaustively examined by Semmler and

Feldstein,

2

who carried out their researches on an oil having the follow-

ing characters:—

Boiling-point at 11 mm from 60° to 215°

Specific gravity at 20° 0-985

Optical rotation + 15° 25'

Refractive index ........ 1-5216

From the fraction boiling at 200° to 210° at 11 mm. a lactone of the
formula C 15 H 2002 was obtained, which the authors have named costus
lactone. It boils at 205° to 211° at 13 mm., and has a specific gravity

(^1) Chem. Zeit., 13 (1883), 1158. (^2) B&richte, 47 (1914), 2433, 2687.